CIS troubleshooting...WUR question...

[cnielsen]

OK, so without going into details... my 73.5 has been giving me some problems. It runs fine and then it runs like crap. I have tested the fuel pressure just sitting with the key in the on position but not running and the pressure is fine. If I start the car with the WUR bypassed, the pressure stays where it should. If I open up the WUR so it is in the fuel circuit, then the car falls on its face and the pressure drops to about a quarter of the original value.

I suspect that the WUR is shot. New ones are $350 plus and they are not even the correct ones...apparently you have to retrofit a 2.7 version... all doable and I think I can find a used 2.7 version to use.

Someone else posted a "how to make an adjustable WUR." Should I do that?

What does the Warm up regulator do? It seems to run fine when it is bypassed, although I have not driven it like this but it idles and takes throttle normally...what if I just leave it disconnected?

Any help would be greatly appreciated... I miss driving my car!

[dougcl]

WUR reduces the fuel "control pressure".

There are two fuel pressures in the CIS system. System pressure and control pressure. System pressure is what the injectors see. Control pressure is bled off from the system pressure, rgulated by the WUR, and allows the sensor plate to move more or less for a given rpm. The lower the control pressure, the higher the sensor plate moves, the richer the mixture. If your car does not run with the WUR in the circuit, it could mean that your mixture has been adjusted without the WUR. Depending on how your are "bypassing" the WUR, that could amount to a rich or lean condition.

Doug

[ianc]

Sounds like the WUR is problematic. Making the WUR adjustable is easily done given a little time, much cheaper than replacing it, and will allow you to fine-tune the cold-running attributes of the system. Give it a try.

ianc